Sheet metal burner and rack assembly for gas fired hot air furnaces



Aprxl 18, 1967 G. WJREZNOR v 3314,10

SHEET METAL BURNER AND BACK ASSEMBLY FOR GAS FIRED HOT AIR FURNACES Filed March 5, 1964 5 Sheets-Sheet 1 32 32 o L as if a INVENTOR. GEORGE W. REZNOR Q ATTORNEY P 1967 G. w. REZNOR SHEET METAL BURNER AND RACK ASSEMBLY FOR GAS FIRED HOT AIR FURNACES 5 Sheets-Sheet 2 Filed March 5, 1964 o m 4 5 2 W 5 4 mm #1 \F |||/|||l A I H E G G R l m F G llilllllld AT TORNEY April 18, 1967 (5. w. REZNOR SHEET METAL BURNER AND BACK ASSEMBLY FOR GAS FIRED HOT AIR FURNACES 5 Sheets-Sheet 5 Filed March 5. 1964 FIG.5

INVENTOR. GEO RGE W. REZNOR AT TO RN EY United States Patent 6 3,314 610 SHEET METAL hUltNlER AND RACK ASSEMBLY FOR GAS FIRED HGT AlR FURNACES George W. Reznor, Mercer, Pan, assignor to international Telephone and Telegraph Corporation, a cor oration of Maryland Filed Mar. 3, 1964, fier. No. 348,931 9 Claims. (Ql. 239--416.5)

This invention relates generally to burner rack assemblies for gas fired hot air furnaces, and has particular reference to an improved burner formed from sheet metal parts.

The improved burner rack assembly comprising the present invention has been designed for use primarily in connection with gas burners of the type wherein hot gases are passed upwardly through a series of vertically disposed, closely spaced, thin walled, heat exchange fire tubes or casings, while at the same time air is forced laterally across and between the tubes or casings in intimate contact with the heated Walls thereof so as to extract heat therefrom, the thus heated air being discharged into an inhabitable enclosure within which the heat exchange assembly is disposed, or, alternatively, being conducted to an inhabitable or other enclosure remote from the heat exchange installation.

There is upon the market at the present time a gas fired heat exchange furnace of the type set forth above wherein the thin walled heat exchange fire tubes are, individually, in the form of relatively flat, thin, rectangular tubular sheet metal, box-like units which are arranged vertically in side-by-side relationship and in positions of substantial contiguity between adjacent units. The upper ends of the fire tube units also are open and thus similarly define a series of elongated narrow slot-like inlet openings which communicate with a combustion chamber therebeneath. Each inlet opening overlies and is in vertical register with an elongated burner which is substantially coextensive with the inlet opening, and which produces a substantially continuous elongated flame jet which is directed upwardly and closely underlies the inlet opening. The various burners are therefore disposed in side-byside spaced relationship so that they will accommodate the respective inlet openings of the heat exchange fire tube units and they communicate effectively with a common gas manifold. The fire tube units are enclosed in a furnace casing and a fan or blower is provided for forcing air through the casing laterally around and between the fire tube units to heat the air by direct heat exchange contact with the fire tube units, after which the thus heated air is discharged to the enclosure to be heated. It is to this type of gas fired heat exchange furnace that the present invention specifically relates.

The invention is specifically concerned with a novel burner rack assembly for a gas furnace of the character briefly outlined above, the assembly serving to support a bank or series of the burners, and being slidable into and out of operative position within the furnace casing so that the same is readily accessible for purposes of inspection, replacement of parts or repair thereof when necessary. When slid into position within the furnace casing beneath the heat exchange fire tubes, the individual burners become vertically aligned with their respective fire tubes.

The burner rack assembly, including the individual burners associated therewith, is largely of sheet metal construction, the burners being of novel design and being comprised of sheet steel stampings which, when operatively assembled upon one another providing composite tubular burner structures which are possessed of advantageous features which have hitherto been unattainable in connection with conventional one-piece cast iron burner structures designed for the same general purpose. The burner support or rack proper likewise is comprised of parts which, in the main, are formed of sheet steel, these including the rack framework which embodies easily separable panels that facilitate burner replacement when necessary, and a secondary air baffle which enhances the flame characteristics of the burners as will be described in detail subsequently. The various sheet metal stampings of the individual burners are permanently assembled upon one another by marginal overlapping beading, as well as by integral ferrule type riveting operations so that spot welding operations are eliminated, while the sheet metal parts of the supporting rack pro-per are fastened together by conventional sheet metal hardware including metal screws and fastening bolts, the arrangement being such as to greatly facilitate assembly operatrons.

Functionally, the individual burners which cooperate to make up the rack assembly are possessed of numerous novel and advantageous features. Because these burners are formed of separate sheet metal stampings, headed and riveted together as previously set forth, the various burner parts are capable of thermal expansion and contraction without developing undue internal stresses which, in the case of conventional cast iron burners, frequently are the cause of permanent warping and the development of cracks in the burner bodies. Thermal expansion and contraction is maintained at a minimum by means of a novel design of the individual sheet metal parts which cooperate to make up each burner, the sheet metal sections of the burner being brought together in coextensive faceto-face contact along wide regions of contact which establish wide-area cooling fins for conducting heat from the composite burner body.

An important feature of the present invention, insofar as the construction of the individual burners is concerned, resides in an elongated nozzle-mixing burner design wherein each burner, in the main, is comprised of two counterpart sheet metal stampings in the form of burner halves which, when assembled upon each other in face-to-face relationship, establish along the mating upper edges thereof a row of closely spaced vertically disposed flame-producing burner ports designed for register with one of the elongated fire tube heat exchange units thereabove. Mating or registering bulges in the two mating stampings establish immediately below the flame producing burner ports an elongated distribution chamber which constitutes a final gas-air mixing chamber in -communication with all of the burner ports. This final distribution chamber is of appreciable width in its medial region and it tapers in opposite direction toward its ends for even proportional distribution of the gas-air mixture to all of the burner ports. The wide medial region of the distribution chamber communicates through a central passage with an initial gas-air mixing chamber of rearwardly flared or tapered design, and the forward end of this initial mixing chamber establishes a manifold orifice for registry with one of a series of gas supply orifice members associated with a gas manifold carried by the burner rack assembly. The final distribution chamber, central passage, initial mixing chamber and manifold orifice are all established by reason of the mating bulges in the two sheet metal burner stampings or halves.

Conventional cast iron burners, as well as sectional sheet metal burners designed for the same purpose as the burner of the present invention, are provided with a single combined distribution and gas-air mixing chamber which is tapered in one direction throughout its entire length and the manifold orifice is disposed at the large forward end of the chamber. Thus, the burner ports which are disposed at the forward end of the burner close to the manifold orifice receive the combustible constituents of the gas-air mixture before they are intimately mixed. The present burner is designed to overcome this limitation which is attendant upon the construction and use of conventional burners and, toward this end, the aforementioned initial gas-air mixing chamber, together with the central chamber leading therefrom to the central region of the final distribution chamber, serves to deliver an intimate mixture of gas and air to the medial region of the distribution chamber, after which the gas-air mixture is divided and distributed in opposite directions to the entire burner length is available for flame producing which extend to the front and rear regions of the burner respectively. By such an arrangement, no single burner port, or group of burner ports, may rob the remaining burner ports of their full quota of the mixture so that even flame distribution throughout the entire length of the burner is afforded.

Another advantage accrues from such delivery of the gas-air mixture to the medial regions of the final distribution chamber. Because, where conventional burners are concerned, a relatively long extent of the inlet end of the single distribution chamber associated with each burner must be employed for gas and air mixing purposes, the row of burner nozzles and ports must commence at a region removed from the inlet end of the burner so that only a portion of the length of the burner may effectively be employed for flame-producing purposes. According to the present invention, because gas and air mixing is accomplished ahead of the final distribution chamber and in a separate mixing chamber, no portion of the final distribution chamber need be reserved exclusively for mixing purposes and therefore the entire burner length is available for flame producing purposes. Because of this, the overall thermal capacity of a burner rack assembly of given size may be appreciably increased.

The design of a sheet metal burner which makes provision for thus feeding an intimate gas-air mixture to the central region of the final distribution chamber constitutes one of the principal features of the present invention.

Another and important feature of the present burner is the provision of a novel arrangement of the burner ports along the upper longitudinal edge of the burner, these ports being of elongated slot-like configuration with the axes of the slots extending longitudinally along the upper edge of the burner. The ports are arranged in two closely spaced rows with the ports of the two rows being paired in a transverse direction. Adjacent ports in each row are also closely spaced in end to end relationship. The remote edges of the paired ports are flared outwardly away from each other. This arrangement of the burner ports is made possible by the novel sectional sheet metal construction of the burner which, briefly, is comprised of three sheet metal parts, namely the two aforementioned sheet metal burner halves, together with a flat burner port division strip, likewise formed of sheet metal. The burner port division strip is sandwiched in between the two burner halves in the burner port area of the burner and the paired burner ports are separated only by the thickness of the sheet metal of the division strip. The burner ports communicate with the aforementioned distribution chamber through respective nozzle passages which are relatively flat and of large expanse. The opposed areas of the two burner halves surrounding the paired bulges which provide the initial gas-air mixing chamber, the central passage, and the final mixing and distribution chamber, are disposed in face-to-face contact, thus providing reinforcing and cooling fins for the burner as a whole. The flared edges of the burner ports eliminate resonance during burner operation and reduce the noise 1V6ll to a minimum. The close pairing of the burner ports and the close spacing of adjacent longitudinally disposed ports establish, in effect, a substantially continuous elongated fia-me which is in coextensive vertical register with the lower inlet end of the heat exchange fire tube which overlies the same. The burner ports are established by a novel system of sheet metal deformation during the stamping operation which is performed on the blanks from which the burner halves are formed, and involving the creation of a series of spacer ribs which assume positions of transverse registry when the two burner halves are assembled upon each other. Finally, the overall configuration of the burner, after assembly of the three sheet metal parts which cooperate to make up the same, is such that a relatively flat or thin elongated construction is provided, thereby enabling a relatively large number of the burners to be positioned in side by side parallel relationship in a burner rack assembly of relatively small dimensions.

A still further and important feature of the present invention resides in the provision of a novel secondary air baffle which closely undenlies the horizontal plane of the various flared burner ports and which serves to direct air around both sides of each burner inwardly toward the bases of the flame jets and into the combustion region of the gas furnace within which the burner rack assembly is installed. By reason of such a secondary air baffle, excess air is supplied to the combustion region of the furnace and serves to combine with any excess gas which may be present in the mixture issuing from the burner ports, thus being conducive toward sto-ichiometric conditions in the combustion chamber and also serving to reduce the height of the flame jets established at such ports and prevent blowing of the flame from the ports with possible extinguishing of the same.

The provision of a burner rack assembly which is comprised of a minimum number of parts, particularly moving parts, and which therefore is unlikely to get out of order; one which is rugged and durable and which therefore is possessed of a relatively long life; one which is capable of ease of assembly and disassembly for pur poses of inspection of parts, replacement or repair thereof; one which, when the burners associated therewith are in operation, is smooth and silent in its operation; one which has a relatively high turn-down range; one which at any turn-down is free from back firing; and one which, otherwise, is well adapted to perform the services required of it, are further desirable features which have been borne in mind in the production and development of the present invention.

With these and other objects and advantages of the invention in view, the invention consists of the novel construction, combination and arrangement of parts shown in the accompanying three sheets of drawings forming a part of this specification.

In these drawings:

FIG. 1 is a perspective view of a gas fired furnace employing the novel burner rack assembly of the present invention, and showing the assembly undergoing installation in the furnace casing;

FIG. 2 is an enlarged perspective View of the burner rack assembly of FIG. 1;

FIG. .3 is an enlarged sectional view taken substantially along the line 33 of FIG. 2 looking in the direction of the arrows;

FIG. 4 is a fragmentary sectional view taken substantially on the vertical plane indicated by the line 44 of FIG. 2, and in the direction indicated by the arrows;

FIG. 5 is an enlarged side perspective view of one of a series of individual burners employed in connection with the present invention;

FIG. 6 is an enlarged sectional view taken substantially along the vertical plane indicated by the line 66 of FIG. 5;

FIG. 7 is an enlarged sectional view taken substantially along the vertical plane indicated by the line 7-7 of FIG. 5;

FIG. 8 is an enlarged sectional view taken substantially along the vertical plane indicated by the line 8--8 of FIG. 5; and

FIG. 9 is an enlarged sectional view taken substantially along the vertical plane indicated by the line 9-9 of FIG. 5;

FIG. 10 is an enlarged sectional view taken substantially along the vertical plane indicated by the line 10 10 of FIG. 5 in the direction indicated by the arrows; and

FIG. 11 is an enlarged sectional view taken substantially along the vertical plane indicated by the line 11-11 of F IG. 2.

Referring now to the drawings in detail and in particular to FIG. 1, an exemplary form of furnace embodying the improved burner rack assembly of the present invention has been shown and designated in its entirety at 10. The furnace is of the gas fired type, and it embodies an upper header section 12, a lower burner section 14, and an intermediate heat exchange section .16. The lower burner section 14 embodies one of the burner rack assemblies of the present invention, the assembly being slidable into and out of the furnace casing in the manner of a drawer. The assembly 18 includes a series of individual burners 24) which are gas fired for the purpose of producing flame jets which are directed through the heat exchange section 16 in order to supply heat thereto. Insofar as the structural arrangement of the furnace 10 is concerned, furnaces of this general type are well known and are widely employed as space heaters for the heating of inhabitable enclosures. Therefore, no claim is made herein to any novelty associated with the furnace 10 per se, the novelty of the present invention residing rather in the novel construction, combination and arrangement of parts associated with the burner rack assembly 18 and which will be described in detail presently.

Briefly, the furnace 10 involves in its general organization an outer furnace casing 22 including a bottom plate or wall 24 which serves to support the burner rack assembly 18 when the latter is operatively installed in the furnace casing, an intermediate rack-like support 26 which serves to support a series of closely spaced heat exchange tubes 28 in the heat exchange section 14, and an upper rack-like support 30 which serves to support the header section 12., The various heat exchange tubes 28 are in the form of generally rectangular and flat hollow sheet metal structures of box-like design which extend vertically between the two supports 26 and 3-1), and have flared upper and lower ends 32 and 34, thus giving a generally venturi shaped configuration to the tubes in transverse vertical cross section. The heat exchange tubes 28 span the distance between the front and rear walls of the casing and are set Within a transverse opening 36 which extends completely through the furnace casing from front to rear thereof. It will be understood that a suitable fan or blower (not shown) is disposed at the rear of the casing 22 and serves to force air transversely through the opening 36 and in between the spaces existing between adjacent heat exchange tubes 28 as is conventional in connection with space heaters of the type illustrated herein. Because of the fact that complete combustion of fuel gas and air takes place in the combustion region of the furnace 10, as will be described in greater detail presently, the header section 10 with 6 which the upper flared ends 32 of the various heat exchange tubes 28 communicate may discharge directly into the enclosure undergoing heating although, if desired, suitable duct work may be employed for conducting the products of combustion from the enclosure.

Referring now to FIG. 2, wherein the burner rack assembly 18 of the present invention has been shown in detail, this assembly involves in its general organization a generally rectangular framework structure including a front burner panel 40, a back burner panel 42, and side panels 44 and 46 respectively, the various panels being formed of relatively heavy gauge sheet metal for purposes of rigidity. The framework afforded by the four panels 40, 42, 44 and 46 is open at its top and bottom and a shallow tray-like structure 48 which, as will be set forth in greater detail presently, constitutes a secondary air baffle for supplying secondary air to the burners 20, extends horizontally across the framework structure and is provided with a series of longitudinally extending slots 50 therein (see also FIG. 3), and through which slots the upper edge regions of the various burners 20 project upwardly with a slight clearance on opposite sides of the burners.

With reference to FIG. 2, the terms front, back and side as applied to the panels 40, 42, 44 and 46 relate to the directional flow of fuel gas into and through the burners 20, the manifold orifice ends of the burners being considered as the front ends thereof. Actually, the burner rack assembly 18 is installed or inserted into the lower burner section 16 of the furnace casing in sidewise fashion, as shown in FIG. 1, so that the herein designated back burner panel 42 is positioned along what commonly is regarded as the front side of the furnace.

The adjacent ends of the various panels 40, 42, 44 and 46 may be fastened together, and the traylike secondary air baffle structure 48 secured in position within the framework of the panels in any suitable manner, the specific details of the particular fastening means not being fully illustrated herein since such means is common in the art of constructing sheet metal structures. Briefly, however, corner joints are made by the provision of appropriately laterally turned attachment flanges, one of which appears at 52 in FIG. 1, and the use of sheet metals fastening screws 54 for holding the parts together. Similarly, the tray-like secondary air baflie structure 48 may be provided with upturned flanges 56 along its marginal edges which are similarly secured to the adjacent panels by sheet metal fastening screws.

The back panel 42 is provided with a series of spaced vertical slots 57 (FIGS. 2 and 11) which loosely receive therein the extreme rear end regions of the various burnera 20, these slots being in alignment and register with the previously mentioned slots 50 in the secondary air baffle structure 48. The forward end of the burners 20 are supported on cylindrical pilot bosses 58 (FIG. 4) provided on the front panel 40 as will be set forth in greater detail subsequently.

Referring now to FIGS. 5 to 10 inclusive, wherein one of the individual burners 20 has been illustrated in detail, each burner is comprised on three principal sheet metal parts or sections including two counterpart burner half-sections 6t and 62, and an intermediate ribbon-like burner nozzleand port-forming divider strip 64. The two half-sections 60 and 62, when brought together on a common meeting plane and secured in face-to-face relationship along certain areas thereof, with the port-forming divider strip 64 sandwiched therebetween along the upper edge of the burner assembly in a manner that will be made clear presently, establish the complete operative burner construction as illustrated in FIG. 5.

Disregarding for the present the sheet metal nature of the burner 2t) and considering only the functional characteristics of the burner, the burner involves in its general organization an elongated tubular distribution chamber 70 (FIGS. 5 and 7) which communicates through a series of relatively thin nozzles 72 which terminate along the upper edge of the burner in respective outwardly flared trough-like burner ports 74. The nozzles 72, as well as the ports 74 associated therewith, are arranged in a longitudinally extending row along the upper edge of the burner, each nozzle and its associated port being divided in the longitudinal direction of the burner by the provision of the ribbon-like divider strip 64. The strip 64 is common to all of the nozzles 72 and ports 74, and it serves as a divider strip therefor, the strip extending vertically downwardly from the horizontal lane of the tips of the various ports 74, completely through the nozzles 72, and having its lower edge terminating within the distribution chamber 7 0.

The ports 74 and nozzles 72, as designated by dual lead lines in the various views of the drawings, are considered for convenience of description and claim terminology herein as being single port and nozzle structures which are divided by the provision of the divider strip 64 into two port and nozzle sections respectively. Actually however, the divider strip 64 establishes two functional rows of nozzles and ports, which are paired transversely of the burner with the ports of each pair being closely adjacent each other and with adjacent longitudinally extending ports being closely positioned in end-to-end relationship.

Still disregarding the sheet metal structure of the burner 20, the elongated distribution chamber 70 communicates medially of its ends with the upper end of a central vertical passage 80, the lower end of the passage, in turn, cornmunicating with the rear end region of an initial gas and air mixing chamber 82. The mixing chamber 82 directly underlies one leg of the distribution chamber 70 and it is of forwardly tapered design. The forward small end of the mixing chamber 82 is provided with an enlarged head portion in the form of a cylindrical rim 84 establishing a manifold orifice 86 and designed for telescopic reception over one of the previously mentioned pilot bosses 58 (FIG. 4) when the burner is installed in the burner rack assembly 18. The two legs of the distribution chamber 70 which exist forwardly and rearwardly of the central vertical passage 80 taper outwardly toward their respective ends as clearly shown in FIG. 5.

Considering now the sheet metal construction of the burner 20, the two burner half-sections 6t) and 62 are generally complementary in their configuration and each is in the form of a stainless sheet steel or aluminum clad steel stamping formed from a flat blank of the sheet steel material. The two stampings are provided with medial bulge regions of such configuration that, when the two stampings are brought together and assembled in operative face-to-face relationship as shown in FIG. 5, these bulges establish therebetween the aforementioned final distribution chamber 70, the central vertical passage 80 and the initial gas and air mixing chamber 82. The for ward leg of the distribution chamber 70 and the underlying mixing chamber 82 are connected together by a flat, dual thickness web 90 having a generally triangular opening 92 extending therethrough. A dual thickness fin portion 92 having a generally triangular opening 93 therein underlies the rear leg of the distribution chamber 70, and an elongated fin 96 underlies the initial gas and air mixing chamber 82.

The sheet metal arrangement of the three sections 60', 62 and 64 of the burner above the distribution chamber 70 presents a novel feature of the present invention and it establishes the aforementioned nozzles 72 and ports 74. Accordingly, the extreme upper edge regions of the two half-sections 60 and 62 are offset outwardly a slight distance from the general plane of the sheet metal blanks from which these sections are formed so that when the sections are brought together these offset edge regions remain spaced from each other a distance approximately equal to the width of the nozzles 72. In FIGS. 6 to 9 inclusive the general planes of the two blanks 60 and 62 have been indicated by the dotted lines a and b respectively and the offset edge ortions above referred to are designated at 94 in FIGS. 6, 7 and 8. Inwardly struck vertical ribs 96 (FIGS. 6 and 7) in the offset regions 94 bear inwardly against the divider strip 64 and establish the various nozzles 72, as well as serving to maintain the offset portions rigidly spaced from each other to thus rigidify the entire burner port region of the burner.

The half-section 62 is formed with a series of small cup-like depressions 98 (FIGS. 5 and 8), the bottom walls of which are pushed outwardly to provide integral tubular tongues in the form of rivet portions 103. The rivet portions 100 project through aligned pairs of holes 102 and 104 provided in the divider strip 64 and halfsection 60 respectively, thus binding the offset portions 94 hard against the intermediate divider strip 64, and further contributing to the rigidity of the burner port region of the assembly. It is to be noted at this point that the successive nozzles 72 are alternately of long and short longitudinal extent and that the tubular rivet portions 100 extend across only the longer nozzles.

In the assembly of the three burner sections 659, 62and 64, spot welding operations are eliminated by a beading process whereby the marginal edge region of the halfsection 69 is beaded around and over the marginal edge region of the half section 62 as indicated at 110, the beading taking place along the entire lower edge 112 of the burner and along the vertical front edge 114 and the arcuate rear edge 116. Similar beading also is effected at 117 and 118 in the vicinity of the triangular openings 92 and 93 respectively.

Referring again to FIG. 2, the burner rack assembly 18 of the present invention is equipped with certain operational and control equipment of a conventional nature and which are only indirectly associated with the invention. Such equipment includes a gas supply manifold 120 having branch distribution nipples 122 which project into the various manifold orifices 86 (FIG. 5) in the usual manner of supplying gas to nozzle mixing burners of the type under consideration. The manifold 120 is supplied with fuel gas, either natural or manufactured, from a supply main 124 through a sectional supply line 126 within which there is interposed any desired control equipment such, for example, as a solenoid valve 128, a pressure regulating valve 130, and a shut-off cock 132. Conventional pilot equipment designated in its entirety at 134 may be tapped into the supply line 126 downstream from the shut-off valve 132 and includes the usual perforated pilot tube 136 (FIG. 4) which spans the distance etween the various burners 20.

The herein described burner rack assembly 18 of the present invention is susceptible to manufacturing Operations as a package unit at the factory, rather than in the field. In the interests of safety in handling and so as to prevent damage thereto, the assembly may be shipped separately and installed in the furnace casing 22 after the latter has been mounted in position in a given installation. When inserted sidewise, as previously described, in the lower burner section 14 of the furnace 10, each burner will underlie one of the heat exchange tubes 28 for direction of the flame issuing therefrom directly into the tube for internal heating purposes. The tubes 28 thus constitute fire tubes which receive their heat from the elongated burner flame jets therebeneath.

The individual burners 20 are particularly advantageous in that each burner presents a longer substantially continuous flame jet than has been possible with conventional burners designed for the same purpose. This is made possible by the provision of the initial tapered gas and air mixing chamber 82 which receives primary gas and air at the manifold orifice 86 and effects intimate mixing of these gaseous constituents of combustion before they are delivered to the medial region of the final distribution chamber 70. Since it therefore is not necessary to assign 'any portion of this latter distribution chamber to an exclusive mixing function, the entire length of the chamber may be ported from the front end to the rear end thereof. Although there may be some intermixing of gas and air within this chamber 70, the chamber functions essentially as a distribution chamber and even those burner ports 74 which directly oppose or overlie the central vertical passage 80 will be supplied with a gas air mixture which is capable of supporting combustion With out further intermixing. The supply of secondary air through the longitudinally extending slots 50 afforded by the secondary air bafl'le 48 (FIG. 3) to the bases of the various flame jets issuing from the burner ports '74, in combination with the flared side Walls of the ports, are conducive toward a firmly seated flame jet which will not blow away from the ports and thus be subject to becoming extinguished. Furthermore, the excess of air which is supplied through the slots 50 will combine with any unburned gas which may issue from the ports. This excess air is carried upwardly into the overlying heat exchange tubes which thus may constitute extensions of the combustion chamber which exists immediately above the burner ports 74 so that final combustion of such excess gases may take place at regions Well above the burner orts.

p The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.

I claim:

1. A sheet metal gas burner for producing an elongated substantially continuous horizontally elongated flame jet adapted to be positioned directly beneath the lower open end of a vertically disposed open-ended and similarly elongated heat exchange tube for heating the tube internally, said burner comprising in combination: two horizontally elongated counterpart sheet metal half-sections of similar peripheral configuration disposed in face-toface relationship along a common meeting plane, said half sections being formed with mating bulges in the medial regions thereof which, in combination with each other, establish a horizontally elongated internal distribution chamber, said half'sections each being provided with linear straight horizontally extending upper edges which lie in a common horizontal plan-e, the upper edge regions of said half-sections being offset laterally outwardly from the meeting plane of said half-sections in opposite directions, at flat sheet metal divider strip disposed between said laterally offset upper edge regions, means for securing said burner half sections together comprising a major portion of the peripheral edge of one of said burner halfsections overhanging and being beaded around the adjacent portion of the peripheral edge of the other burner half-section in interlocking relationship, one of said laterally oifset portions being formed with a series of clamping tongues which project through said divider strip and the other laterally offset portion and serve to clamp the two laterally offset portions and divider strip rigidly together, said offset upper edge regions being further formed with a series of inwardly struck protube rances which bear inwardly against the divider strip and serve to center the latter between the offset upper edge regions in spaced relationship with respect thereto, thus establishing a longitudinally extending row of closely spaced tubular burner nozzles which communicate at their lower ends with said distribution chamber and terminate in open burner ports along the upper edges of the half-sections, and which ports and nozzles are divided by said divider strip, said mating bulges further establishing an initial gas and air mixing chamber in communication with said distribution chamber, said gas and air mixing chamber terminating in a manifold orifice adapted for register with a gas supply distribution nipple.

2. A sheet metal gas burner as set forth in claim 1, wherein the extreme upper edges of said burner half-sections are flared outwardly away from each other.

3. A sheet metal gas burner for producing an elongated substantially continuous horizontally elongated flame jet adapted to be positioned directly beneath the lower open end of a vertically disposed open-ended and similarly elongated heat exchange tube for heating the tube internally, said burner comprising in combination two horizontally elongated counterpart sheet metal half-sections of similar peripheral configuration dis-posed in face-to-face relationship along a common meeting plane, said halfsections being formed with mating bulges in the medial regions thereof which, in combination with each other, establish a horizontally elongated internal distribution chamber, said half-sections each being provided with l nearly straight horizontally extending upper edges which lie in a common horizontal plane, the Upper edge regions of said half-sections being offset laterally outwardly from the meeting plane of said half-sections in opposite directions, a flat sheet metal divider strip disposed between said laterally offset upper edge regions, a row of holes located in and extending through said divider strip, said offset upper edge regions being formed with a series of inward- 1y struck, longitudinally spaced, vertically disposed ribs which bear inwardly against the divider strip and serve to center the latter between the offset upper edge regions in spaced relationship with respect thereto, thus establishing a longitudinally extending row of closely spaced tubular burner nozzles which communicate at their lower ends with said distribution chamber and terminate in open burner ports along the upper edges of the half sections, and which ports and nozzles are divided by said divider strip, said mating bulges further establishing an initial gas and air mixing chamber and which underlies the distribution chamber, passageway means for connecting one end of said mixing chamber with the medial region of said distribution chamber, cylindrical manifold orifice means terminating the other end of said mixing chamber adapted for register with a gas supply distribution nipple, one of said laterally offset portions being formed with a series of longitudinally spaced tubular rivet portions which project through said holes and are beaded around the edges of the latter for securing said laterally offset portion and divider strip rigidly together, the peripheral edge of one of said half-sections, exclusive of the upper linearly straight upper edge thereof, overhanging the adjacent peripheral edge of the other half-section and being beaded therearound in clamping relationship.

4. A sheet metal gas burner as set forth in claim 6 and wherein the portion of said burner which extends be tween the distribution chamber and the underlying gas and air mixing chamber constitutes a dual-thickness Web which extends from the forward edge of the burner to the juncture region between the distribution chamber and the gas and air mixing chamber.

5. A sheet metal gas burner as set forth in claim 7 wherein said dual-thickness web is formed with an opening therethrough, the metal of one thickness of said web being beaded around the other thickness of the web in the marginal regions of said opening.

6. A burner rack assembly adapted for insertion into a furnace casing and, when so inserted, to underlie a series of heat-exchange tubes for supplying heat internally to the latter, said assembly comprising an open rectangular rack frame including vertical front, back and side panels connected together at adjacent ends, said front panel being formed with a horizontal row of spaced openings therethrough, said openings surrounding rearwardly extending cylindrical pilot bosses, said back panel being formed with a series of spaced vertically disposed slots in longitudinally opposed relationship with respect to said openings. a series of elongated gas burners extending between and supported on said front and back panels, each burner comprising a hollow tubular body defining an upper longitudinally extending distribution chamber substantially spanning the distance between said front and back panels, a lower longitudinally extending gas and air mixing chamber underlying the front portion of said distribution chamber, and a vertical passage establishing communication between the rear end of said mixing chamber and the medial region of said distribution chamber, the forward end of said mixing chamber being formed with a cylindrical flange defining a manifold orifice for the introduction of gas and induced air into the mixing chamber, said cylindrical flange being telescopically received over one of said pilot bosses in supported relationship, the rear end of said burner body being formed with a thin fin-like edge region projecting into one of said slots in the back panel in supported relationship, said hollow tubular body further defining a series of closely and longitudinally spaced tubular burner nozzles which communicate at their lower ends with said distribution chamber and which terminate at their upper ends in upwardly opening burner ports, said burner ports lying in a common horizontal plane and the series of nozzles and their associated ports substantially bridging the distance between said front and back panels, a horizontally disposed tray-like secondary air baffle common to all of the burners and spanning the distance between said front and back panels, said baflle being formed with a series of longitudinally extending slots therein through which the tubular burner nozzles project upwardly, and from the side edges of which the nozzles are spaced, said baffle being disposed slightly below the level of said burner ports, and a gas supply manifold positioned exteriorly of said front panel and fixedly supported on said rack frame, said manifold including a series of supply nipples projecting into said manifold orifices through said pilot bosses.

7. A burner rack assembly as set forth in claim 6 and wherein the longitudinally extending slots in said secondary air baffle are formed with upstanding side flanges which are spaced from said burner nozzles on opposite sides thereof.

8. A burner rack assembly adapted for insertion into a furnace casing and, when so inserted, to underlie a series of heat-exchange tubes for supplying heat internally to the latter, said assembly comprising an open rectangular rack frame including vertical front, back and side panels connected together at adjacent ends, said front panel being formed with a horizontal row of spaced openings therethrough, said openings surrounding rearwardly extending cylindrical bosses, said back panel being formed with a series of spaced vertically disposed slots in longitudinally opposed relationship with respect to said openings, a series of elongated gas burners extending between and supported on said front and back panels, each burner comprising a hollow tubular body defining an upper longitudinally extending distribution chamber substantially spanning the distance between said front and back panels, a lower longitudinally extending gas and air mixing chamber underlying the front portion of said distribution chamber, and a vertical passage establishing communication between the rear end of said mixing chamber and the medial region of said distribution chamber, the forward end of said mixing chamber being formed with a cylindrical flange defining a manifold orifice for the introduction of gas and induced air into the mixing chamber, said cylindrical flange being telescopically received over one of said cylindrical bosses in supported relationship, the rear end of said burner body being formed with a thin fin-like edge region projecting into one of said slots in the rear panel in supported relationship, said cylindrical bosses and slots constituting the sole supporting means for said burners in the rack assembly, said hollow tubular body further defining a series of closely and longitudinally spaced tubular burner nozzles which communicate at their lower ends with said distribution chamber and which terminate at their upper ends in upwardly opening burner ports, a longitudinally extending divider wall extending across each burner nozzle centrally thereof thus establishing a divided port at the upper end thereof, said divided burner ports lying in a common horizontal plane and the series of nozzles and their associated ports substantially bridging the distance between said front and back panels, a horizontally disposed tray-like secondary air baffle common to all of the burners and spanning the distance between said front and back panels, said bafile being formed with a series of longitudinally extending slots therein through which the tubular burner nozzles project upwardly and from the side edges of which slots the nozzlesare spaced, said bafiie being disposed slightly below the level of said burner ports, and a gas supply manifold positioned exteriorly of the front panel and fixedly supported on said rack frame, said manifold including a series of supply nipples projecting into said manifold orifices through said cylindrical bosses.

9. A burner rack assembly adapted for insertion into a furnace casing and, when so inserted, to underlie a series of heat-exchange tubes for supplying heat internally to the latter, said assembly comprising an open rectangular rack frame including vertical front, back and side panels connected together at adjacent ends, said front panel being formed with a horizontal row of spaced openings therethrough, said Opening surrounding rearwardly extending cylindrical pilot bosses, said back panel being formed with a series of spaced vertical disposed slots in longitudinally opposed relationship with respect to said openings, a series of elongated gas burners extending between and supported on said front and back panels, each burner comprising a hollow tubular body defining an upper longitudinally extending distribution chamber substantially spanning the distance between said front and back panels, a lower longitudinally extending gas and air mixing chamber underlying the front portion of said distribution chamber, and a vertical passage establishing communication between the rear end of said mixing chamber and the medial region of said distribution chamber, the forward end of said mixing chamber being formed with a cylindrical flange defining a manifold orifice for the introduction of gas and induced air into the mixing chamber, said cylindrical flange being telescopically received over one of said pilot bosses in supported relationship, the rear end of said burner body being formed with a thin fin-like edge region projecting into one of said slots in the rear panel in supported relationship, said pilot bosses and slots constituting the sole supporting means for said burners in the rack assembly, said hollow tubular body further defining a series of closely and longitudinally spaced tubular burner nozzles which communicate at their lower ends with said distribution chamber and which terminate at their upper ends in upwardly opening burner ports, a longitudinally extending vertical divider wall extending across each burner nozzle centrally thereof and coextensive with the full height of the nozzle, thus establishing a divided port at the upper end thereof, said divided burner ports lying in a common horizontal plane and the series of nozzles and their associated ports substantially bridging the distance between said front and back panels, a horizontally disposed tray-like secondary air baflie common to all of the burners and spanning the distance between said front and back panels, said bafile being formed with a series of longitudinally extending slots therein through which the tubular burner nozzles project upwardly, the lateral rim regions of said divided ports being flared outwardly away from each other, the side edges of said longitudinally extending slots in the baffle being provided with upturned flanges which are spaced laterally from the sides of said nozzles and which extend upwardly to a region slightly below the level of the lateral rim regions of said divided ports, and a gas supply manifold positioned exteriorly of the front panel and fixedly supported on the rack frame, said manifold including a series of supply nipples 13 14 projecting into said manifold orifices through said pilot 2,670,790 3/1954 Marble 158--116 X bosses. 2,828,532 4/1958 Taylor 158-416 X References Cited by the Examiner 2,875,821 3/ 1959 Allen 15 81 15 UNITED STATES PATENTS 3,002,552 10/1961 Griffin 158116 543,568 7/1895 Bryan 126 91 5 3,177,923 4/1965 Hlne et a1 158-116 1,656,549 I/ 1928 Warmack. 2,044,528 6/1936 Guhl M. HENSON WOOD, JR., Prlmary Exammer.

2,541,710 2/1951 Miller 239-566 X VAN C. WILKS, Assistant Examiner. 

1. A SHEET METAL GAS BURNER FOR PRODUCING AN ELONGATED SUBSTANTIALLY CONTINUOUS HORIZONTALLY ELONGATED FLAME JET ADAPTED TO BE POSITIONED DIRECTLY BENEATH THE LOWER OPEN END OF A VERTICALLY DISPOSED OPEN-ENEDED AND SIMILARLY ELONGATED HEAT EXCHANGE TUBE FOR HEATING THE TUBE INTERNALLY, SAID BURNER COMPRISING IN COMBINATION: TWO HORIZONTALLY ELONGATED COUNTERPART SHEET METAL HALF-SECTIONS OF SIMILAR PERIPHERAL CONFIGURATION DISPOSED IN FACE-TOFACE RELATIONSHIP ALONG A COMMON MEETING PLANE, SAID HALF SECTIONS BEING FORMED WITH MATING BULGES IN THE MEDIAL REGIONS THEREOF WHICH, IN COMBINATION WITH EACH OTHER, ESTABLISH A HORIZONTALLY ELONGATED INTERNAL DISTRIBUTION CHAMBER, SAID HALF-SECTIONS EACH BEING PROVIDED WITH LINEAR STRAIGHT HORIZONTALLY EXTENDING UPPER EDGES WHICH LIE IN A COMMON HORIZONTAL PLANE, THE UPPER EDGE REGIONS OF SAID HALF-SECTIONS BEING OFFSET LATERALLY OUTWARDLY FROM THE MEETING PLANE OF SAID HALF-SECTIONS IN OPPOSITE DIRECTIONS, A FLAT SHEET METAL DIVIDER STRIP DISPOSED BETWEEN SAID LATERALLY OFFSET UPPER EDGE REGIONS, MEANS FOR SECURING SAID BURNER HALF SECTIONS TOGETHER COMPRISING A MAJOR PORTION OF THE PERIPHERAL EDGE OF ONE OF SAID BURNER HALFSECTIONS OVERHANGING AND BEING BEADED AROUND THE ADJACENT PORTION OF THE PERIPHERAL EDGE OF OTHER BURNER HALF-SECTION IN INTERLOCKING RELATIONSHIP, ONE OF SAID LATERALLY OFFSET PORTIONS BEING FORMED WITH A SERIES OF CLAMPING TONGUES WHICH PROJECT THROUGH SAID DIVIDER STRIP AND THE OTHER LATERALLY OFFSET PORTION AND SERVE TO CLAMP THE TWO LATERALLY OFFSET PORTIONS AND DIVIDER STRIP RIGIDLY TOGETHER, SAID OFFSET UPPER EDGE REGIONS BEING FURTHER FORMED WITH A SERIES OF INWARDLY STRUCK PROTUBERANCES WHICH BEAR INWARDLY AGAINST THE DIVIDER STRIP AND SERVE TO CENTER THE
 6. A BURNER RACK ASSEMBLY ADAPTED FOR INSERTION INTO A FURNACE CASING AND, WHEN SO INSERTED, TO UNDERLIE A SERIES OF HEAT-EXCHANGE TUBES FOR SUPPLYING HEAT INTERNALLY TO THE LATTER, SAID ASSEMBLY COMPRISING AN OPEN RECTANGULAR RACK FRAME INCLUDING VERTICAL FRONT, BACK AND SIDE PANELS CONNECTED TOGETHER AT ADJACENT ENDS, SAID FRONT PANEL BEING FORMED WITH A HORIZONTAL ROW OF SPACED OPENINGS THERETHROUGH, SAID OPENINGS SURROUNDING REARWARDLY EXTENDING CYLINDRICAL PILOT BOSSES, SAID BACK PANEL BEING FORMED WITH A SERIES OF SPACED VERTICALLY DISPOSED SLOTS IN LONGITUDINALLY OPPOSED RELATIONSHIP WITH RESPECT TO SAID OPENINGS, A SERIES OF ELONGATED GAS BURNERS EXTENDING BETWEEN AND SUPPORTED ON SAID FRONT AND BACK PANELS, EACH BURNER COMPRISING A HOLLOW TUBULAR BODY DEFINING AN UPPER LONGITUDINALLY EXTENDING DISTRIBUTION CHAMBER SUBSTANTIALLY SPANNING THE DISTANCE BETWEEN SAID FRONT AND BACK PANELS, A LOWER LONGITUDINALLY EXTENDING GAS AND AIR MIXING CHAMBER UNDERLYING THE FRONT PORTION OF SAID DISTRIBUTION CHAMBER, AND A VERTICAL PASSAGE ESTABLISHING COMMUNICATION BETWEEN THE REAR END OF SAID MIXING CHAMBER AND THE MEDIAL REGION OF SAID DISTRIBUTION CHAMBER, THE FORWARD END OF SAID MIXING CHAMBER BEING FORMED WITH A CYLINDRICAL FLANGE DEFINING A MANIFOLD ORIFICE FOR THE INTRODUCTION OF GAS AND INDUCED AIR INTO THE MIXING CHAMBER, SAID CYLINDRICAL FLANGE BEING TELESCOPICALLY RECEIVED OVER ONE OF SAID PILOT BOSSES IN SUPPORTED RELATIONSHIP, THE REAR END OF SAID BURNER BODY BEING FORMED WITH A THIN FIN-LIKE EDGE REGION PROJECTING INTO ONE OF SAID SLOTS IN THE BACK PANEL IN SUPPORTED RELATIONSHIP, SAID HOLLOW TUBULAR BODY FURTHER DEFINING A SERIES OF CLOSELY AND LONGITUDINALLY SPACED TUBULAR BURNER NOZZLES WHICH COMMUNICATE AT THEIR LOWER ENDS WITH SAID DISTRIBUTION CHAMBER AND WHICH TERMINATE AT THEIR UPPER ENDS IN UPWARDLY OPENING BURNER PORTS, SAID BURNER PORTS LYING IN A COMMON HORIZONTAL PLANE AND THE SERIES OF NOZZLES AND THEIR ASSOCIATED PORTS SUBSTANTIALLY BRIDGING THE DISTANCE BETWEEN SAID FRONT AND BACK PANELS, A HORIZONTALLY DISPOSED TRAY-LIKE SECONDARY AIR BAFFLE COMMON TO ALL OF THE BURNERS AND SPANNING THE DISTANCE BETWEEN SAID FRONT AND BACK PANELS, SAID BAFFLE BEING FORMED WITH A SERIES OF LONGITUDINALLY EXTENDING SLOTS THEREIN THROUGH WHICH THE TUBULAR BURNER NOZZLES PROJECT UPWARDLY, AND FROM THE SIDE EDGES OF WHICH THE NOZZLES ARE SPACED, SAID BAFFLE BEING DISPOSED SLIGHTLY BELOW THE LEVEL OF SAID BURNER PORTS, AND A GAS SUPPLY MANIFOLD POSITIONED EXTERIORLY OF SAID FRONT PANEL AND FIXEDLY SUPPORTED ON SAID RACK FRAME, SAID MANIFOLD INCLUDING A SERIES OF SUPPLY NIPPLES PROJECTING INTO SAID MANIFOLD ORIFICES THROUGH SAID PILOT BOSSES. 